Regulating system for dynamo-electric machines



. 1,633,808 June- 1927' R. E. DOHERTY REGULATING SYSTEM FOR DYNAMO ELECTRIC MACHINES Filed May 9, 1925 Fig.1.

Irm/entorl Robert E. Doherty,

I! is; fittorney.

Patented June 28,, 1327.

o n STATES PATENT OFFICE.

301mm: n-nggflfir, or soon. new mnxnssxenon rose-rinses annc'rnro cou- PANY, Anew roan conronemoni REGULATING SYSTEM. FOR. DYNAMO -ELEOTBIG MACHINES.

Application filed Kay 9,

6 tance power transmission systems.

In connection with the problem of, longdistance power transmisslon, the voltage stability of the synchronous machines, that is, the inherent regulation, becomes -apredominating factor. To illustrate, the ultimate maximum power which. can be trans mitted over a 500 mile, 220,000 volt, threephase line of ordinary construction, is,

about greater when assuming generating apparatus with no tendency foixvoltage change during load changes than when us ing synchronous eneratxirs of ordinary de" sign and 01': new capacity relative to the 'load tr nsmitted. An alternator controlled by eve a sensitive re ulator, such for ex ample, as a Tirrill or vi ratory-type of regulator, behaves for sudden changes in load 'much the same as if it were operating eta constant field current. The terminal voltage must first change and cause a change in thesetting of the contacts, bciorc a corresponding change in the exciting current takes place. It is this time lag in the operation of the regulator that imposes a. sern ons limitation upon the output of the long distance power trimsn'nssion lines because of he inability of theregulator to hold uo he voltage uponsudden application of ion It is, therefore, desirable to stiffen the synchronous machine, that is to hold up the terminal voltage during the period between application of sudden load and the final action of the voltage regulator.

An object of my invention is to provide a novel regulating system to momentarily stiffen the synchronous rnachines of a high voltage long-distance power transmission line inorder to increase the power limit of the line during the transient following a sudden increase in load.

Briefl described, my nvention comprises means or rapidly increasing the voltage in the excitation circuit of synchronous cl ternators or condensers during field current transients,; caused by sudden application of a loader short circuit, so as to prevent a too rapid decrc of the excitation at a time when lo to have the excitation 1925. Serial m.- eases.

maintained on the machine. ,Preferably,

I accomplish these results hy providing an auxiliary source excitetion in series with the ordinary silent-wound exciter in the ex f citation circuit of synchronous machine. This auxiliary source of: excitation, such as a series-type exoiter, is designed for quick action, as by laminating the field poled and operating undersnturui'cd, so as to provide a voltage to maintain the current induced in the excitation circuit on sudden application of load upon the synchronous machine.

nection with the accompanying drawing, in-

which Fig. 1 i a diagrammatic representation of a transmission line and generating station with regulating means embodying my invention, and Fig. his c diagram of a modification of the system shown in Fig. 1;

Referring to i, 3 denotes a threephnsc alter-netingcurrcn neratcr providing the ener v iii-u ri over stepup transiorn line composing 1';ll1(,i. i do W :1 ot The iiclo. Nliltllih gized by means 0 wound excite-r 7 design, and an an; root-current e1: 8 poles connected in secircuit The energies may he controlled oy means of an ordinary "Iirriil-type voltage re ulator 9 or any other similarly sensitive type of regulator 1n combination with a resistance 10 operating on the field of exciter 7. I

Before discussing the operation of the system it is important to note that the ordinary combination of an'exciter with' a Tirci ing circuit. utor 1 1 ener- A ec ay he of ordinary seriesavound (l1- ianrinated field h the excitation shuntv on icy the exciter 7 rill-type of regulator will not produce the 1 excitation to coiinterhalance the armature 'reaction of an alternator quick! enough for.

an alternator, the sudden change in armature.

up the flux interlinking those turns.

reaction induces an increase in the field current to halance the armature reaction. However, the voltage of a shunt excite! is not capable or rising instantaneously and the alternator field current heoins to die down before the erzciter can build up the necessary voltage to maintain it. The difficulty lies in the fact that the flux: of the shunt exciter links the turns of the shunt Winding. In order to increase the induced voltage of the exciter, it necessary to build If the cxciter is compounded the series and shunt field windings link with the same magnetic circuit. Hence any sudden increase in ampere turns due to the series Winding will, by transformer action, induce a corresponding decrease in the shunt field ampere turns, thus maintaining, for the moment, the same magnetic flux.

The operation of the regulating system consists broadly in partially balancing the effect of armature reaction in an alternator by maintaining for a limited time the instantaneous increase in excitation current occasioned by sudden application of load. An unsaturated series excite): responds quicl:- ly to a field current change and supplies a voltage proportional to its current. The \;oltage introduced in the excitation circuit by the series ercitcr is in a direction to :tuno tion as an equivalent negative resistance. An unsaturated series exciter 8 or any similarly sensitive source of excitation is interposed in the PnCllfiilGIl circuit of alternator 1 so that during any field transient the rics exciter will tend to hnild up and maintain the alternator field current until the regulator 9 filnctions to increase the voltage of the shunt circitcr 7.

The shunt-excitcr with the regulator is therefore instrumental in rcgulaling; the ex citation for steadystate conditions. that is, when a permanent condition is ol'ituincd; during the iuuzrvsl hctwccn tv' permanent conditions, that is, when transient phenom one occur, the sense. ivc, quick acting source s a voltage to nmintli n s L of excitation supplie the field current tron ion-o.

Sin e the duration of the transient is nicasured hy the ratio of inductance to resist-- ance in the circuit, it follows that by introducing a negative resistance equal to the positive resistance, or ohmic resistance, the duration would be indefinitely increased. It is not desirable to go to this limit, but it has been found that if during any field transient the equivalent negative rcsistance is adjusted to be slightly less than the equivalent positive resistance of the circuit, the series exciter would tend tobuild up and maintain the alternator Ield current until the regulator causes the shunt cxciter to increase its voltage,

in Fig. 52 is shown a similar arrangement of apparatus as hereinheforc discussed, in which like numerals have been used to refer to corresponding parts. This ligure, however, shows the field winding 12 of the shunt euciter 7 separately excited. Any suitable source, for example a battery, may he used; a direct-current shunt-Wound generator 13 being indicated. This arrangement is found convenient in order to prevent any tendency toward instability in the shunt excite-r T when it is found necessary to make the negative resistance more nearly equal to the positive resistance for a particular alternator held. The separately excited l'icld winding will insure a constant source. of excitcr field voltage independent of voltage change in the alternator excitation circuit. The shunt exciler 7 may he re ulatcd in the mrdinary Way by an automatic Voltage regulator 5).

With the introduction of the series excitcr 8 in the excitation circuit, the alternator 1 will now tend to maintiiin its terminal voltage at the normal value due to the prolonged duration of the licld transient and will require le s duty by the regulator 9 on account of the cumulative incrc in the voltage of the series cxciter "following an increase in the excitation current by the shunt exciter 7 due to the operation of the re ulator.

ll hile I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications ma he made within the scope of my invention and I, therclorc, aim in the appended claims to cover all such changes and modifications that full within the true spirit and scope of my invention.

What I claim as new and desire to sccurc by Rollers Patent of the United Slat-cs is:

l. The comhination of a synchronous dynamoclcctric nurhine, an excitation circuit therefor, :1 main source of electrical energy :lo said 'rcitation'circuit, and an auxiliary source or excitation interposed in said cxcitation circuit responsive to current transients induced in the excitation circuit of said synchronous machine.

The combination with an clcclric power circuit, of a synchronous dynamo-electric machine connected to supply said cirruit, an excitation circuit therefor, a main source of electrical energy for said excitation circuit, regulator responsive to an electrical condition of said power circuit for controlling said excitation circuit, and an auxiliary source of excitation interposed in said excitation circuit responsive to current transients induced in the excitation circuit of said synchronous machine.

3. The combination with an electric power transmission system, of a synchronous dynamo-electric machine for supplying power thereto, an excitation circuit therefor, a main source of electrical. energy for said exloo ' means responslve 1,eae,sos

citation circuit, a regulator responsive to the voltage of said synchronous machine for controlling the stead state current in said excitation circuit, and an auxiliary source of excitation interposed in said excitation circuit responsive to current transients induced in the excitation circuit of said synchronous machine. 5,4. In combination, an alternating'currerit dynamo-electric machine, a field winding therefor, and means comprising a dynamoelectric machine for impressing upon said field winding an excitation voltagecomprising one component the value of which is substantially unaffected by current changes in .said field winding and another compo- "nent the value of which varies substantially Simultaneously with changes of" current in said field windingf 5. In combination, an alternating current generator, a field winding therefor, fa source of electrical energy for said field winding,

to an electrical condition of said enerator for regulating said source of electrical energy, and an auxiliary source of excitation responsive to current transients induced in the field winding of said generator.

6. In combination, a synchronous dynamo electric machine, a field winding therefor, a shunt-type direct-current exciter energizing said field winding, and an unsaturated series-type direct-current eXciter in series with said shunt-type exciter'.

7. In combination, an alternating-current generator, a field winding therefor, a shunttype direct-current excitcr energizing said field winding, a regulator responsive to the voltage of said generator influencing the voltage of said exciter, and a quick-acting s eries type direct-current excite!" in series with said shunt-type exciter.

8. A regulating system comprising an alternating-current synchronous dynamo-electric machine, a source of excitation for said synchronous machine, a regulator operative in response to an electrical condition of said synchronous machine for controlling the voltage of said. source, and means interposed in circuit with said source of excitation for lengthening the duration of current transients induced. in said excitation circuit to maintain the voltage. of said synchronous machine during the interval necessary for the operation of said regulator to be effective.

9. A regulating system comprising a synchronous dynamo-electric machine, a main source of excitation therefor, a regulator responsive to the voltage of said synchronous machine i'or controlling the voltage of said main source of excitation and an auxiliary source of excitation for sustaining an instantaneous increase in excitation current substantially to balance the armature reaction occasioned by sudden change in load upon said synchronous machine.

10, A regulating system comprising a syn ichronons alternatingcurrent generator, a hold circuit therefor, a shunt-type dynamoelectric machine connected for energizing said field circuit, a 'egulator responsive to the voltage otsaid. synchronous generator for controlling the voltage of said dynamo electric machine, and a quick-actin series type exciter interposed in said fiel circuit for maintaining the voltage of said genei ator upon sudden application of load.

In witness whereof, I have hereunto set my hand this 7th day of May, 1925.

ROBERT nonnnirr. 

